Method and apparatus for wireless network load emulation

ABSTRACT

A method and system for emulating a user population for wireless local area network access point performance, optimization and configuration testing. The number of stations, data volume and related variables are programmed by a command and control computer, with a load emulator then offering a realistic station population and data traffic load to the wireless access point under test. Multiple load emulators may be deployed for the emulation and testing of very large networks.

CROSS REFERENCE TO A RELATED APPLICATION

[0001] This application is entitled to, and claims the benefit of,provisional application No. 60/326,174 filed 25 Apr. 2002.

TECHNICAL FIELD OF THE INVENTION

[0002] The present invention relates generally to the field of datacommunications, and, more specifically, to the performance,optimization, and configuration testing of wireless local area networkaccess points.

BACKGROUND OF THE INVENTION

[0003] Many, including development engineers, network administrators,and network testing organizations, have occasion to test the performanceof wireless local area networks. The accepted practice of testingwireless local area networks is to install numerous computers withwireless network capability, then associate, authenticate, and presentrequests for data to a wireless hardware device called an access point,sending and receiving data streams over a high frequency radio channel.This common practice is expensive, driven by the cost of the manycomputers, and is not easily configurable for the commonly neededvariety of user population sizes and data traffic loads.

SUMMARY OF THE INVENTION

[0004] The present invention, employing what is termed a load emulator,overcomes the considerable expense and inadequacies of the acceptedpractice of testing wireless local networks by emulating a programmablenumber of virtual stations, associating each virtual station with theaccess point, authenticating the user for security purposes, andtransferring data designed to elicit performance parameters over awireless link.

[0005] The load emulator method and apparatus (or system) has manyadvantages over the accepted practice, providing variable and realisticnetwork load conditions, allowing network builders to quickly determinethe efficiency and capacity of an access point under test.

[0006] Three components make up the load emulator test environment, 1) acomputer to command test parameters and display results, 2) the loademulator, and 3) the wireless access point under test. With thisconfiguration one can emulate from 1 to 255 virtual stations withrealistic network addresses, network association procedures, userauthentication processes, and transfer of data over the wirelessnetwork.

[0007] From this test procedure, a variety of information is collected,analyzed and displayed. One can use this information to analyze theaccess point under test, make configuration adjustments to optimizeoverall performance, determine access point capacity, establishboundaries of the target user population size, conduct performancecomparisons of network equipment manufacturers, and acquire other usefuldata and information.

[0008] The objects, features, and advantages of the present inventionwill be apparent to the reader from the foregoing and the appendedclaims and as the ensuing detailed description and discussion proceedsin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a block diagram illustrating a typical test environmentembodying the principles of the present invention and comprising a load,emulator as disclosed herein connected to a command and report computerand to a wireless access point under test;

[0010]FIG. 2 is a block diagram illustrating the internal functionalelements of the load emulator and the connections of the load emulatorto the command and report computer and to the access point under test,and

[0011]FIG. 3 is a flow diagram illustrating the operations of the loademulator functional elements along with load emulator command and reportcomputer interaction.

DETAILED DESCRIPTION OF THE INVENTION

[0012] Referring now the drawings, a representative wireless accesspoint test environment embodying the principles of the present inventionand utilizing a load emulator is depicted in FIG. 1 and identified byreference character 20. In this system command and report computer 22 isconnected by a serial wired connection 23 called a command lineinterface (CLI) to a load emulator 24 also encompassing thoseprinciples. The load emulator is connected over a wireless radio link 26conforming to the 802.11 standard to an access point 24 under test. Theaccess point is typically, but not necessarily, wired into a traditionalenterprise data network 28.

[0013] The functional elements of the novel and representative loademulator 24 are depicted in FIG. 2. These are: a controller 30 forcommand/report computer 22, a virtual station processor 32, access pointinput/output controller 34, and a log and statistics file 36.

[0014] System 20 is readied by initializing load emulator 24. Toinitialize the load emulator, a body of virtual station parameters isentered into command and report computer 22 either manually, or from atable of parameters stored in that computer. This station profile blockof information contains a media access control (MAC) address, Internetprotocol (IP) address, a station name and password, and packetized datafor the transmission to the access points being tested. The MAC and IPaddresses are specified over a range which accommodates the desirednumber of virtual stations. Packet sizes are specified over an allowablerange, and are unique for each virtual station, thus realisticallyemulating a typical station population.

[0015] The virtual station processor 32 is responsible for execution ofthe test scripts 34, performing initial access point authenticationthrough the input/output controller 34, the calculation of elapsed time,the recording of success or failure conditions, and the logging of theinformation into the log and statistics file 36. With successfulauthentication based on a virtual station name and password, the virtualstation processor 32 initiates an association procedure 44 through theinput/output controller 34. The input/output controller communicatesdirectly with the access point 28 under test over 802.11 wireless link26. Virtual station association elapsed time is calculated, success orfailure recorded and resulting information loaded into log andstatistics file 36. With successful authentication and associationprocesses completed, virtual station processor 32 transfers a packet ofrealistic data to the input/output controller 34 for transmission overthe wireless 802.11 link 26 to the access point 38 under test. Elapsedtime and throughput of the data transfer is calculated with resultingdata being stored in the log and statistics file 36.

[0016] This process is repeated in sequence for each virtual stationuntil completion of the test run. At the conclusion of the test runcontroller 30 causes test data to be exported from log and statisticsfile 36 to command and report computer 22 for analysis of the recordeddata and display of test results.

[0017]FIG. 3 depicts internal operations of the load simulator 24,beginning with station block initialization process 38 and stationprofile block definition process 40 by the external command and reportcomputer 22. In load emulator 24 the station profile block 41 is loadedwith a MAC address, an IP address, and packetized data for transmission.A repeat loading process 42 tracks the number of virtual stations to betested and determines when the last station has been emulated. Once allvirtual station profile blocks have been loaded, active virtual stationprocess 44 is enabled. A virtual station name and password are passed toinput/output controller 34 and presented to the access point 28 undertest for authentication of the particular virtual station. Elapsed timeand success or failure of the virtual station authentication is storedin log and statistics file 36. Upon successful authentication virtualstation association is attempted by the initiate/end association process46. Elapsed time and success or failure of the virtual stationassociation is stored in log and statistics file 36.

[0018] With successful authentication and association of the virtualstation, a programmable sized packet of data is transferred to theinput/output controller 34 for transmission over the 802.11 wirelesslink 26 to the access point 28 being tested (process 47). Elapsed timeof the data transfer is calculated, error conditions reported and datathroughput recorded in log and statistics file 36.

[0019] A second repeat process 48 sequentially processes all virtualstations, one after the other, by triggering activate virtual stationprocess 43 until the last virtual station has been emulated. Uponcompletion of the test run, the repeat loading process 48 signalscompletion to log and statistics file 36. The log and statistics fileinformation is then transferred by export log file process 50 across CLI23 to the command and report computer 22, which analyzes the information(process 52), and displays the results (process 54).

[0020] The invention may be embodied in many forms in addition to thosedisclosed herein without departing from the spirit or essentialcharacteristics of the invention. The present embodiments are thereforeto be considered in all respects as illustrative and not restrictive,the scope of the invention being indicated by the appended claims ratherthan by the foregoing description. All changes which come within themeaning and range of equivalency of the claims are intended to beembraced therein.

What is claimed is:
 1. a method of evaluating the performance of anetwork access point, said method comprising the steps of: creating avirtual station for the access point under test; transmittingperformance evaluation data from the virtual station to the access pointunder test; and recovering from the access point performance datagenerated in response to the evaluation data transmitted to the accesspoint under test.
 2. A method as defined in claim 1 in which the samevirtual station creating mechanism is employed to created a differentvirtual station for association with each of a number of network accesspoints and wherein a block of performance association data istransferred from at least some of those virtual stations to associatedaccess points under test to evaluate performance at those access points.3. A method as defined in claim 1 wherein data recovered from the accesspoint under test is stored in a log and statistics file.
 4. A method asdefined in claim 3 in which the stored data for the access point undertest is exported to a computer for analysis.
 5. A method as defined inclaim 1 in which the virtual station is authenticated and then isassociated with the access point under test as a prerequisite totransmitting information from the virtual station to the access pointunder test.
 6. A method as defined in claim 1 in which data istransferred from the virtual station to the access point under test byway of an input/output controller.
 7. A method as defined in claim 6 inwhich there is a wireless connection between the input/output controllerand the access point under test.
 8. A test environment for evaluating alocal area network, said environment comprising: a network access pointto be tested; a load emulator which is loaded with test point data andwhich can be associated with the test point; a data transfer connectionbetween the load emulator and the test point; and a computer which isconfigured to program and control the operation of the load emulator. 9.A test environment as defined in claim 8 in which the load emulatorcomprises a virtual station processor with a data block for transmissionto a network access point under test.
 10. A test environment as definedin claim 8 in which the load emulator comprises a log and statisticsfile for storing test results and/or other data exported from the accesspoint under test.
 11. A test environment as defined in claim 8 in whichthe computer has the capability of analyzing test results and/or otherdata exported from the access point under test.
 12. A load emulator foruse in the evaluation of a network test point, said load emulatorcomprising: a corresponding virtual station which comprises a stationprofile and which is operatively associatable with the access pointunder test; a command and report computer; a first controlleroperatively associated with the computer and the virtual stationprocessor for controlling the transfer of commands and data between thecomputer and the virtual station processor; a virtual stationprocess-to-test point communications link; a second, input/outputcontroller for controlling the flow of data via the communications linkbetween the virtual station processor and the corresponding access pointunder test; and a log and statistics file for test results and/or otherdata exportable from the access point under test.
 13. A method forevaluating a network by testing multiple network access points, saidmethod comprising the steps of: loading station profiles seriatim intoeach of multiple virtual station processors corresponding on aone-to-one basis with the network access points to be tested; andactivating the virtual station processors in turn to: (a) authenticatethe virtual station processor; (b) associate the authenticated virtualstation processor with the corresponding access point under test; and(c) initiate the transfer of access point evaluation data from thetheretofore associated virtual station processor to the access pointunder test.
 14. A method as defined in claim 13 in which: a test resultdata is subsequently exported from each access point that issuccessfully associated with the corresponding virtual stationprocessor; and the test result data is analyzed and the results of theanalysis displayed.
 15. A method as defined in claim 13 in which thetest result data exported from each access point that is successfullyassociated with the corresponding virtual station processor is stored ina log and statistics file.